Cranial anchoring and positioning system and method

ABSTRACT

A cranial anchor system configured to attach to an opening in a cranium includes an anchor member. The anchor member has a middle anchor portion and a lower anchor portion coupled to and disposed in a downward direction relative to the middle anchor portion. The lower anchor portion has a plurality of contact members, each of which have a leg that extends at least partially in the downward direction, a tab connected to the leg, and a rib disposed between the leg and the tab. The system further includes an outer sheath and an inner sheath disposed within the outer sheath and slidable relative to the outer sheath.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a '371 National Stage Entry of PCT application No.PCT/US18/23065, which claims the benefit of U.S. Provisional ApplicationNo. 62/476,157 filed Mar. 24, 2017, both of which are incorporated byreference herein in their entireties.

TECHNICAL FIELD

A system and method for affixing an anchoring system to a cranium andaccessing structures within the brain prior to and as part of a medicalor surgical procedure is shown and described.

BACKGROUND

During a medical procedure it is desired to precisely and securelyposition and support a medical device in a fixed location relative tothe patient. For example, during medical procedures that require accessto the cranial cavity an external anchoring system is affixed to theskull. This anchoring system creates a fixed point of reference relativeto the patient, thereby allowing for a higher degree of control andprecision during a medical procedure. In addition, the anchoring systemallows the medical device to access a location within a patient whilemaintaining operational control external to the patient. The anchoringsystem is attached to the skull by fasteners and includes a channel thataccesses a bore in the skull. The channel can accommodate instrumentssuch as a surgical probe or endoscope.

Existing cranial anchoring systems are secured to the skull byconventional methods such as the use of bone screws. While providingsecure anchoring to the cranium is important, it is less than optimal toinflict any more trauma than is necessary to the skull during aprocedure. For example, U.S. Pat. No. 8,845,655 describes a guideinstrument that is placed over a burr hole in a patient's skull toenable operation on the patient's brain. Screws are employed to securethe base plate to the skull of a patient. The guide instrument requiresmultiple bone fixation screws to be placed in the patient's skull. Thisassembly increases the time it takes to position and attach theinstrument and to remove the instrument from the patient. As a result,the patient's skull not only has a burr hole drilled therein, but mustreceive additional trauma from threaded bone fixation screws.

SUMMARY

An improved cranial anchoring system is disclosed. In one aspect of thedisclosure, a cranial anchor system configured to attach to an openingin a cranium includes an anchor member that is elongated along a firstaxis. The anchor member includes a middle anchor portion defining amiddle anchor recess that extends about the first axis and a loweranchor portion coupled to and disposed in a downward direction relativeto the middle anchor portion along the first axis. The lower anchorportion includes a plurality of contact members that together define alower anchor recess. Each of the plurality of contact members has a legthat extends from a bottom of the middle anchor portion, each leg havingan angular bend defining an upper and a lower section of the leg, and arib mounted to the leg. The system further includes an outer sheath thatis elongated along a second axis and defines a first channel, the outersheath including a joint configured to be at least partially disposedwithin the middle anchor recess and the lower anchor recess such thatthe joint is rotatable within the middle anchor recess and the loweranchor recess. The system also includes an inner sheath disposed withinthe first channel and slidable relative to the outer sheath along thesecond axis. The inner sheath defines a second channel that is elongatedalong the second axis.

In another aspect of the disclosure, a cranial anchor apparatus isconfigured to attach to an opening in a cranium. The anchor apparatus iselongated along a first axis. The apparatus includes a middle anchorportion that defines a middle anchor recess that extends about the firstaxis. The apparatus also includes a lower anchor portion coupled to anddisposed in a downward direction relative to the middle anchor portionalong the first axis. The lower anchor portion includes a plurality ofcontact members that together define a lower anchor recess. Each of theplurality of contact members have a leg that extends from a bottom ofthe middle anchor portion, the leg having an angular bend defining anupper and a lower section of the leg, and a rib mounted to the leg.

In yet another aspect of the disclosure, a cranial anchor apparatus isconfigured to attach to an opening in a cranium. The anchor apparatus iselongated along a first axis. The apparatus includes a middle anchorportion defining a middle anchor recess that extends about the firstaxis. The apparatus also includes a lower anchor portion coupled to anddisposed in a downward direction relative to the middle anchor portionalong the first axis. The lower anchor portion includes a plurality ofcontact members that together define a lower anchor recess. Each of theplurality of contact members has a leg that extends from the bottom ofthe middle anchor portion, each leg having an angular bend defining anupper and a lower section of the leg, and a rib mounted to the leg. Theapparatus further includes a support ring connected to the middle anchorportion and disposed about the first axis and below at least a portionof each of the plurality of contact members.

Another aspect of the present disclosure is directed to methods of usingthe system and apparatuses described herein, including steps ofpositioning a cranial anchoring system onto a patient's skull.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional side view of a cranial anchoring system,according to an aspect of the present disclosure.

FIG. 2 is a perspective view of a cranial anchoring apparatus, accordingto an aspect of the present disclosure.

FIG. 3 is a side view of a cranial anchoring system, according toanother aspect of the present disclosure.

FIG. 4A is a perspective view of a cranial anchoring apparatus,according to another aspect of the present disclosure.

FIG. 4B is a side view of the cranial anchoring apparatus illustrated inFIG. 4A.

FIG. 4C is a top view of the cranial anchoring apparatus illustrated inFIG. 4A.

FIG. 5A is an exploded isometric view of a locking assembly, accordingto an aspect of the present disclosure.

FIG. 5B is a side view of the locking assembly illustrated in FIG. 5A.

FIG. 6 is a cross sectional view of the anchor member with the lockingassembly and the outer sheath secured thereto.

FIG. 7 is a perspective view of a cranial anchoring system, according toanother aspect of the present disclosure.

FIG. 8 is a perspective view of a lower portion of the cranial anchoringsystem illustrated in FIG. 7, according to an aspect of this disclosure.

FIG. 9 is a cross sectional view of the cranial anchoring systemillustrated in FIG. 7, according to an aspect of this disclosure.

FIG. 10 is a perspective view of the cranial anchoring systemillustrated in FIG. 7 with a portion of a locking assembly positionedwithin, according to another aspect of this disclosure.

FIG. 11. is a side view of the cranial anchoring system illustrated inFIG. 10 with a locking assembly positioned within, according to anotheraspect of this disclosure.

FIGS. 12A-12C illustrate positions of a lower portion of the cranialanchoring system illustrated in FIG. 7.

DETAILED DESCRIPTION

FIG. 1 shows a side view of a cross section of a cranial anchoringsystem 100 such as the type used in a surgical procedure for removingintracranial fluid and tissue. As shown in FIG. 1, the system includes areference array 112 similar to reference arrays used by existingsurgical navigation systems such as, but not limited to, the MedtronicStealthStation™, Brainlab Curve™, or Stryker Nav3i™. In this view, anexemplary cranial anchoring system 100 is shown that can be positionedwithin a burr hole H of a skull S.

The cranial anchoring system 100 includes an anchor member or base plate200, an outer sheath 104, an inner sheath 106, a height adjustmentdevice 108, a locking member 110, and the reference array 112. Thereference array 112 is operatively mounted onto the anchor member 200 toprovide a reference point for the position of the anchoring system 100on the skull S of a patient. Other components may be included within thesystem 100, for example, to provide additional support, to increasemaneuverability, or to provide other functionality to facilitate theremoval of intracranial fluid and tissue.

The anchor member 200 is configured to attach to the burr hole H of theskull S as will be described in greater detail below. The anchor member200 provides a platform for the anchoring system 100 to be mounted tothe skull S allowing for access and interface with the inside of theskull S.

Referring to FIG. 2, the anchor member 200 includes an upper anchorportion 202, a middle anchor portion 204, and a lower anchor portion206. The upper anchor portion 202, the middle anchor portion 204, andthe lower anchor portion 206 are axially aligned along longitudinal axis50, such that the upper anchor portion 202 is above the middle anchorportion 204, and the middle anchor portion 204 is above the lower anchorportion 206. The terms “above” and “below,” as used herein, describe thepositions of certain components relative to one another and are thusapproximations. The terms “above”, “upper”, or “uppermost” mean aposition that is closer to an uppermost portion of the cranial anchoringsystem 100, such as the inner sheath 106, and the terms “below”,“bottom”, or “bottommost” mean a position closer to a bottommost portionof the cranial anchoring system 100, such as the lower anchor portion206 of the anchor member 200.

The middle anchor portion 204 includes an inner edge 205, a firstsurface 217, and a second surface 207 spaced from the first surface inan axial direction A1. The axial direction A1 extends along thelongitudinal axis 50. The inner edge 205 extends circumferentially aboutthe longitudinal axis 50, thereby partially defining a middle anchorrecess 209 within the middle anchor portion 204. The inner edge 205 ofthe middle anchor portion 204 defines a hole that may be circular inshape.

The lower anchor portion 206 extends downward from the second surface207 of the middle anchor portion 204. The lower anchor portion 206includes a plurality of contact members 208 that together define a loweranchor recess 201, each of which have a leg 203 that extends at leastpartially in the axial direction A1. Each contact member 208 has aninner contact surface 210, an outer contact surface 212, a rib 214, anda tab 216. Each rib 214 extends between the leg 203 and the tab 216 andis attached to the outer contact surface 212, and each tab 216 isattached to the bottommost end of the leg 203. Each rib 214 and each tab216 extend at least partially outwardly relative to axis 50 in a radialdirection R1. The radial direction R1 is perpendicular to the axis 50.Each tab 216 may be angled up relative to the radial direction R1towards an uppermost part of the lower anchor portion 206 so as to forman acute angle relative to the respective contact member 208.Alternatively, tab 216 may be angled down relative to the radialdirection R1 towards a bottommost part of the lower anchor portion 206so as to form an obtuse angle relative to the respective contact member208. Alternatively still, tab 216 may extend along, or substantiallyalong the radial direction R1 so as to form a 90° degree angle relativeto the axis 50. In some aspects, lower anchor portion 206 may includetabs that extend up, down, along radial direction R1, or any combinationthereof. In some aspects, each rib 214 may be attached to the outercontact surface 212 without being attached to each corresponding tab216. In some aspects, each contact member 208 may include a differentconfiguration relative to the other contact members 208.

Multiple configurations of contact members 208 having ribs 214 and tabs216 attached thereto may be incorporated into the lower anchor portion206. For example, the lower anchor portion 206 may include any number ofcontact members 208, such as 12 contact members, so long as the contactmembers sufficiently attach the anchor member 200 to the skull S. Infurther examples, lower anchor portion 206 may include 8, 9, 10, 11, 13,14, 15, or 16 contact members. Further, each contact member 208 may havea different configuration. For example, each contact member 208 may onlyinclude either a rib 214 or a tab 216. Alternatively, each contactmember 208 may include both a rib 214 and a tab 216, or include neithera rib 214 nor a tab 216.

The contact members 208 may be outwardly biased, e.g. cantilevered,spring-loaded, or otherwise resiliently biased, such that whencompressed radially inwardly, a force is exerted by the contact members208 in the outwardly radial direction R1. For example, when the anchormember 200 is positioned within the burr hole H, the contact members 208may exert a retention force on the edge of the burr hole H on the skullS and on the inner surface of the burr hole H in the skull S proximateto the burr hole H.

In some aspects of the disclosure, the ribs 214 may include a sharp edge215. The sharp edge 215 may be configured to lightly penetrate a marginof the skull S when the anchor member 200 is positioned within the holeH. Sharp edge 215 functions to minimize or prevent movement of theanchor member 200 during the surgical procedure. Tabs 216 may also hookunder the skull S to minimize or prevent outward migration of the anchormember 200. Anchor member 200 can be inserted into hole H by pushing inthe axial direction A1 while rotating about axis 50.

Referring to FIGS. 1 and 2, the upper anchor portion 202 extends fromthe first surface of the middle anchor portion 204, and extendscircumferentially about the longitudinal axis 50. An inner surface 211of the upper anchor portion 202 defines a threaded region, such as aninternally threaded region, and an upper anchor opening 213. The upperanchor opening 213 aligns with the middle anchor recess 209 of themiddle anchor portion 204 along axis 50. An anchor outer surface 219 ofthe upper anchor portion 202 may define grooves, gear teeth, or thelike, configured to allow the anchor member 200 to be gripped orotherwise manipulated.

The outer sheath 104 includes a joint 104 a and an upper outer sheathportion 104 b. The joint 104 a is positioned within the middle anchorrecess 209 of the middle anchor portion 204. The joint 104 a is at leastpartially rotatably coupled to the inner contact surfaces 210 of thecontact members 208, such that the outer sheath 104 rotates within theanchor member 200. The joint 104 a defines a lower sheath channel thatextends along a sheath longitudinal axis 60. The sheath longitudinalaxis 60 extends from a bottommost end of the outer sheath 104 to anuppermost end of the inner sheath 106.

The joint 104 a is spherical in shape. The positioning of the joint 104a within the middle anchor portion 204 will act as a fulcrum formovement of the joint 104 a. For example, the movement of the joint 104a within the middle anchor portion 204 may be similar to a ball andsocket joint, such that the joint 104 a is restricted from movement inthe axial direction A2 and the radial direction R2, but is free to movecircumferentially.

The upper outer sheath portion 104 b is positioned above the joint 104 aalong the sheath longitudinal axis 60. The upper outer sheath portion104 b defines an upper sheath channel. The upper sheath channel alignswith the lower sheath channel along a sheath axial direction A2. Thesheath axial direction A2 extends along the longitudinal axis 60. Themovement of the joint 104 a relative to the anchor member 200 isminimized by contact between the joint 104 a and the locking member 110.In some aspects of the disclosure, the joint 104 a rotates up to 30degrees relative to axis 50, such that the sheath longitudinal axis 60is 30 degrees offset from the anchor longitudinal axis 50.

The inner sheath 106 is slidably disposed within the lower sheathchannel and the upper sheath channel of the outer sheath 104. The innersheath 106 defines an inner sheath channel that extends through theinner sheath 106 in the sheath axial direction A2. The inner sheath 106extends through the anchor member 200 to provide access to the insidethe skull S. Inner sheath 106 may be configured to extend inside theskull S a distance that provides access to target locations within theskull S.

In some aspects of the present disclosure, a conduit 107 may be coupledto a lower end of the inner sheath 106. The conduit 107 defines aconduit channel that aligns with the inner sheath channel. The conduitchannel may have the same diameter as the inner sheath channel, or theconduit channel may have a diameter that is greater or smaller than thediameter of the inner sheath channel. The conduit channel may bedisposed about axis 60 or it may be offset from axis 60. The conduitchannel extends from the inner sheath channel to provide for greateraccess within the skull S.

The height adjustment device 108 is operationally coupled to the innersheath 106, and rotatably coupled to the outer sheath 104. Rotation ofthe height adjustment device 108 about the sheath longitudinal axis 60allows movement of the inner sheath 106 in the sheath axial directionA2. The height adjustment device 108 is rotatably coupled to the upperouter sheath portion 104 b. For example, height adjustment device 108may be fixed to the outer sheath 104 and include a threaded innersurface that mates with a threaded outer surface of the inner sheath106, such that rotation of the height adjustment device 108 about theaxis 60 moves the inner sheath 106 relative to the outer sheath 104along the axis 60.

The locking member 110 defines a threaded region 114, such as anexternally threaded region, and an internal locking surface 116. Theregion 114 of the locking member 110 is configured to mate with thethreaded region of the inner surface 211 of the upper anchor portion202, such that rotational movement of the locking member 110 about thelongitudinal axis 50 secures the locking member 110 onto the anchormember 200.

The internal locking surface 116 of the locking member 110 is configuredto engage the joint 104 a of the outer sheath 104. Contact between theinternal locking surface 116 and the outer sheath 104 restricts orminimizes movement of the outer sheath 104 relative to the anchor member200. For example, this contact restricts axial, radial, andcircumferential movement relative to axis 50 of the outer sheath 104within the anchor member 200. The restriction in movement is caused byfriction between the internal locking surface 116 and the outer sheath104, grooves or teeth positioned on the internal locking surface 116and/or outer sheath 104, or other structural features that may beincorporated to limit movement.

The cranial anchoring system 100 may further include a pump 503, such asan aspiration or suction pump. The pump 503 may be coupled to an upperend of the inner sheath 106 via a flexible tube 505. The pump 503 may beperistaltic or continuous in nature, producing a suction force to drawintracranial fluid, tissue, or other intracranial matter, through theinner sheath 106 to an exterior of the skull S.

The cranial anchoring system 100 may also include a vibratory orultrasonic mechanism (not shown). The vibratory mechanism may be coupledto an uppermost end of the anchoring system 100 and provide a vibratoryor ultrasonic force to the inner sheath 106. The provided force assistsin breaking up the fluid and tissue within the skull S, therebyminimizing the size of the particles to extract.

The cranial anchoring system 100 may further include an obturator (suchas obturator 313 described below). The obturator may be slideablydisposed within the inner sheath channel and extend out of the lowermostend of the inner sheath 106. The obturator may be configured to minimizeor prevent unwanted coring of brain tissue during initial insertion ofthe inner sheath 106 within the skull S.

FIGS. 3 through 6 illustrate an alternate embodiment of a cranialanchoring system. Portions of the embodiment disclosed in FIGS. 3through 6 are similar to aspects described above in FIGS. 1 and 2 andthose portions function similarly to those described above. Cranialanchoring system 300 includes an anchor member or base plate 400, anouter sheath 304, an inner sheath 306, a height adjustment device 308, alocking assembly 310, and a reference array 312. The cranial anchoringsystem 300 may be positioned within the burr hole H of the skull S in asubstantially similar manner as cranial anchoring system 100.

In some aspects of the disclosure, the system 300 may include a secondreference array 315, shown in FIG. 3, slidably mounted within the innersheath 306 or, alternatively, operatively mounted to the obturator. Inother aspects of the disclosure, anchoring system 300 may include only asingle reference array 315 attached to inner sheath 306, oralternatively, to the obturator. The arrays 312, 315 provide spatialreference information to a surgical navigation system (not shown). Thenavigation system locates the spatial reference point of the arrays312,315 to determine the positioning of the inner sheath 306 relative topatient anatomy. The arrays 312, 315 can be configured to work with avariety of navigational systems that are known and used in the art. Thenavigation system may also receive information related to magneticresonance imaging (MRI), computed tomography (CT), ultrasound imaging,or other image data set of the inside of the skull S. The navigationsystem provides real time information that allows the surgeon toprecisely adjust the cranial anchoring system 300 to target a locationwithin the patient.

The outer sheath 304, the inner sheath 306, the height adjustment device308, the locking assembly 310, and the reference array 312 may beconfigured and aligned substantially similarly as the outer sheath 104,the inner sheath 106, the height adjustment device 108, the lockingmember 110, and the reference array 112 of the cranial anchoring system100. Cranial anchoring system 300 may further include a spacer member311 positioned between the locking assembly 310 and the outer sheath304, such that the bottommost end of the locking assembly 310 interfaceswith a lower end of the outer sheath via the spacer member 311.

The cranial anchoring system 300 may further include an obturator 313.The obturator 313 may be slidably disposed within the inner sheathchannel defined by the outer sheath 304 and the inner sheath 306. Theobturator 313 may extend out of the lowermost end of the inner sheath306. Obturator 313 may be incorporated into cranial anchoring system 100in a similar manner. The obturator 313 may also interface with a specialreference array.

Referring to FIGS. 4A and 4B, the anchor member 400 includes an upperanchor portion 402, a middle anchor portion 404, and a lower anchorportion 406. The upper anchor portion 402, the middle anchor portion404, and the lower anchor portion 406 are axially aligned alonglongitudinal axis 70, such that the upper anchor portion 402 is abovethe middle anchor portion 404, and the middle portion 404 is above thelower anchor portion 406. The upper anchor portion 402 and the middleanchor portion 404 may have a substantially similar structure to theupper anchor portion 202 and the middle anchor portion 204 of cranialanchoring system 100.

The lower anchor portion 406 extends from the middle anchor portion 404and includes a plurality of contact members or feet 408 and a supportring 420. Each of the contact members 408 may include either or both ofa rib 414 and a tab 416, and may include multiple configurations asdescribed above with respect to contact members 208 of cranial anchoringsystem 100.

The support ring 420 extends at least partially in an axial direction A3and circumferentially about longitudinal axis 70. The axial direction A3extends along the longitudinal axis 70. A plurality of support arms 422extend upwards from support ring 420. Each support arm 422 is spacedcircumferentially about the longitudinal axis 70 and positioned inbetween the contact members 408. Each support arm 422 is coupled to thelower ring portion 424.

The lower ring portion 424 is positioned at a bottommost end of thesupport arms 422 in the axial direction A3. The lower ring portion 424may align with the bottommost end of the contact members 408. In otheraspects of this disclosure, the lower ring portion 424 may be positionedabove or below (See FIG. 4B) the bottommost end of the contact members408 in the axial direction A3.

The lower anchor portion 406 also includes a plurality of anchor ribs430 that extend outwardly in a radial direction R3 along the loweranchor portion 406 from the uppermost end to the bottommost end. Theradial direction R3 is substantially perpendicular to the axialdirection A3. In an aspect of this disclosure, each of the anchor ribs430 extend along each of the support arms 422 so as to strengthensupport arms 422.

The outer sheath 304 is configured to be positioned within the middleanchor portion 404 and supported by the lower anchor portion 406 of theanchor member 400. More specifically, the outer sheath 304 may besupported by the contact members 408, the support arms 422, the lowerring portion 424, or combinations thereof.

Referring to FIG. 4C, which illustrates a top view of the anchor member400, the lower anchor portion 406 further includes a plurality ofprotrusions 432 that extend in the radial direction R3 from an inneranchor surface 434. The protrusions 432 may be spaced circumferentiallyabout the lower anchor portion 406 and may be positioned in between eachof the contact members 408.

FIGS. 5A and 5B illustrate an exploded perspective view and side view ofthe locking assembly 310, respectively, according to an aspect of thisdisclosure. The locking assembly 310 includes a threaded top 502 and aslotted bottom 504. The threaded top 502 defines a threaded region 506,such as an externally threaded region. The threaded region 506 isconfigured to mate with a threaded region 436, such as an internallythreaded region (See FIG. 4C) of the upper anchor portion 402 so as tosecure the locking assembly 310 to the anchor member 400.

The slotted bottom 504 is configured to extend at least partially intothe lower anchor portion 406 of the anchor member 400 in the axialdirection A3. The slotted bottom 504 may include a lower locking surface508 and an outer surface 510. The lower locking surface 508 may engageand provide a downward force relative to axis 50 to the outer sheath304, which bears on the lower ring portion 424 and pushes the contactmembers 408 outwardly in the radial direction R3, thereby furthersecuring the outer sheath 304 within the anchor member 400. In this way,slotted bottom 504 functions similarly to spacer member 311 in that bothinterface between the locking members and the outer sheath. In an aspectof this disclosure, the slotted bottom 504 may be conical shaped, orotherwise shaped to maximize the contact between the lower lockingsurface 508 and the outer sheath 304 when the slotted bottom 504 ispositioned within the anchor member 400.

The outer surface 510 of the slotted bottom 504 may define a pluralityof slots 512 spaced circumferentially around the slotted bottom 504.Each of the slots 512 may be positioned to align with a correspondingprotrusion 432 of the lower anchor portion 406. The alignment of eachslot 512 with each protrusion 432 minimizes or prevents circumferentialmovement of the slotted bottom 504 relative to the anchor member 400.

FIG. 6 illustrates a cross sectional view of the anchor member 400 withthe locking assembly 310 and the outer sheath 304 secured thereto,according to an aspect of this disclosure. The lower locking surface 508is positioned at a bottommost end of the slotted bottom 504 and isconfigured to contact the outer sheath 304. The contact between thelower locking surface 508 and the outer sheath 304 may restrict orotherwise limit axial, radial, and circumferential movement of the outersheath 304 when the outer sheath 304 is positioned within the anchormember 400. Further, while the locking assembly 502 is being secured tothe anchor member 400, movement of the slotted bottom 504 relative tothe outer sheath 304 may be substantially limited to axial movement dueto the alignment of each slot 512 of the slotted bottom 504 with eachprotrusion 432 of the anchor member 400. Limiting movement between thesplit bottom 504 and the outer sheath 304 minimizes any disruption theslotted bottom 504 may have to the position, including the rotationalposition, of the outer sheath 304 while the outer sheath 304 is beingsecured to the anchor member 400.

FIGS. 7 through 12 illustrate an alternate embodiment of a cranialanchoring system. Portions of the embodiment disclosed in FIGS. 7Athrough 11 are similar to aspects described above in FIGS. 1 through 6and those portions function similarly to those described above. Cranialanchoring system 600 includes an anchor member or base plate 700, anouter sheath 604, an inner sheath (not shown), a locking nut 608, alocking assembly 610, and a reference array (not shown). The cranialanchoring system 600 may be positioned within the burr hole H of theskull S in a substantially similar manner as the cranial anchoringsystems 100 and 300.

The outer sheath 604, the inner sheath, and the reference array may beconfigured and aligned substantially similarly as the outer sheaths 104and 304, the inner sheaths 106 and 306, and the reference arrays 112 and312 of the cranial anchoring systems 100 and 300. The locking nut 608may be configured to lock the inner sheath within the outer sheath 604,preventing axial movement between them. The cranial anchoring system 600may also include an obturator (not shown) configured and alignedsubstantially similarly as the obturator 313 of cranial anchoring system300.

Referring to FIGS. 8 and 9, the anchor member 700 includes an upperanchor portion 702, a middle anchor portion 704, and a lower anchorportion 706. The upper anchor portion 402, the middle anchor portion404, and the lower anchor portion 406 are axially aligned alonglongitudinal axis 80, such that the upper anchor portion 702 is abovethe middle anchor portion 704, and the middle portion 704 is above thelower anchor portion 706. The upper anchor portion 702 and the middleanchor portion 704 may have a substantially similar structure to theupper anchor portions 202 and 402 and the middle anchor portions 204 and404 of cranial anchoring systems 100 and 400.

The lower anchor portion 706 extends from the middle anchor portion 704and includes a plurality of contact members 708 and a support ring 720.Each of the contact members 708 may include a leg 703 and a rib 714. Theleg 703 and the rib 714 may include multiple configurations as describedabove with respect to contact members 208 and 408 of cranial anchoringsystems 100 and 400. The support ring 720 may be configured and alignedsubstantially similarly to the support ring 420 of the cranial anchoringsystem 400.

Each leg 703 has an angular bend 705 that defines an upper section 713of the leg 703 and a lower section 716 of the leg 703. The lower section716 of the leg 703 extends from the angular bend 705 to an end 719 ofthe leg 703. The end 719 may define a bottommost end of each of theplurality of contact members 708 in an axial or downward direction A4.The axial direction A4 extends along the longitudinal axis 80. The lowersection 716 includes a lower surface 717, which may comprise a planarconfiguration. In an aspect, an angle Φ formed at the angular bend 705between the lower section 716 and the upper section 713 of the leg 703may form an obtuse angle.

Each rib 714 may include a sharp edge 715 that extends along a length ofeach rib 714. Each rib 714 may be mounted on either the upper section713 or the lower section 716 of the leg 703, or both the upper section713 and the lower section 716. Each rib mounted on the lower section 716of the leg 703 may extend from the angular bend 705 towards the end 719of the leg 703. Each sharp edge 715 may extend parallel to the lowersurface 717. Each rib 714 mounted on the upper section 713 may extendfrom the angular bend 705 toward the middle anchor portion 704.

The plurality of contact members 708 may be spaced circumferentiallyabout the longitudinal axis 80. Each rib 714 may be mounted on the uppersection 713 of the leg 703 or the lower section 716 of the leg 703. Inan aspect, each consecutive pair of the plurality of contact members 708includes a rib 714 mounted on the upper section 713 of the leg 703 and arib 714 on the lower section 716 of the leg 703. For example, the ribs714 may alternate between being mounted on the upper section 713 and thelower section 716 for every contact member 708 spaced about the loweranchor portion 706.

Referring to FIG. 9, the lower anchor portion 706 further includes aplurality of protrusions 732 that extend in a radial direction R4 froman inner anchor surface 734. The radial direction R4 is substantiallyperpendicular to the axial direction A4. The protrusions 732 may bespaced circumferentially about the lower anchor portion 706 and may bepositioned in between each of the contact members 708.

The locking assembly 610 includes a threaded top 802 and a slottedbottom 804. The split top 802 defines a threaded region 806, such as anexternally threaded region. The threaded region 806 is configured tomate with a threaded region 736, such as an internally threaded regionof the upper anchor portion 702 so as to secure the locking assembly 610to the anchor member 700.

The slotted bottom 804 is configured to extend at least partially intothe lower anchor portion 706 of the anchor member 700 in the axialdirection A4. The slotted bottom 804 may include a lower locking surface808 and an outer surface 810. The lower locking surface 808 causes theouter sheath 604 to move in the A4 direction, which results in the outersheath 604 forcing the contact members 708 outwardly in the radialdirection R4. After the contact members 708 have been sufficientlydeflected in the radial direction R4, the outer sheath 604 bears on thesupport ring 720, thereby further securing the outer sheath 604 betweenthe lower locking surface 808 and the support ring 720. In an aspect ofthis disclosure, the slotted bottom 804 may be conical shaped, orotherwise shaped to maximize the contact between the lower lockingsurface 808 and the outer sheath 604 when the split bottom 804 ispositioned within the anchor member 700.

FIGS. 10 and 11 illustrate the anchor member 700 with the slotted bottom804 positioned within, according to aspects of this disclosure. Theslotted bottom 804 is transparent in FIG. 10 and the anchor member 700is transparent in FIG. 11 for illustrative purposes. The outer surface810 of the split bottom 804 may define a plurality of slots 812 spacedcircumferentially around the split bottom 804. Each of the slots 812 maybe positioned to align with a corresponding protrusion 732 of the loweranchor portion 706. The alignment of each slot 712 with each protrusion732 minimizes or prevents circumferential movement of the split bottom804 relative to the anchor member 700.

The lower locking surface 808 is positioned at a bottommost end of theslotted bottom 804 and is configured to contact the outer sheath 604.The contact between the lower locking surface 808 and the outer sheath604 may restrict or otherwise limit axial, radial, and circumferentialmovement of the outer sheath 604 when the outer sheath 604 is positionedwithin the anchor member 700. Further, while the locking assembly 702 isbeing secured to the anchor member 700, movement of the split bottom 804relative to the outer sheath 604 may be substantially limited to axialmovement due to the alignment of each slot 812 of the slotted bottom 804with each protrusion 732 of the anchor member 700. The locking assembly610 may be sized such that each protrusion 732 is received within eachslot 812 prior to the threaded region 806 of the split top 802 beingmated with the threaded region 736 of the upper anchor portion 702,thereby preventing the locking assembly 610 from being screwed togetherwith the anchor member 700 while they are misaligned. In an aspect, thesplit bottom 804 may extend from the lower anchor portion 706 to theupper anchor portion 702 of the anchor member 700 when each protrusion732 is positioned within each slot 812. Limiting movement between theslotted bottom 804 and the outer sheath 604 minimizes any disruption thesplit bottom 804 may have to the position, including the rotationalposition, of the outer sheath 604 while the outer sheath 604 is beingsecured to the anchor member 600.

The plurality of contact members 708 are configured to be actuated froman initial position, to a first position, and to a second position. FIG.12A illustrates the initial position of the plurality of contact members708. In the initial position, the contact members 708 are biased in theradial direction R4 prior to entering the burr hole H or otherwise notin use.

FIG. 12B illustrates the first position of the contact members 708 asthey enter the burr hole H. In the first position, each contact member708 extends inward in the radial direction R4 such that each lowersurface 717 extends substantially parallel to a wall of the burr hole H.The sharp edge 715 of each rib 714 may contact the wall of the burr holeH. It will be appreciated that as the contact members 708 enter the burrhole H in the axial direction A4, the contact members 708 are compressedinward the radial direction R4.

FIG. 12C illustrates the second position of the contact members 708. Inthe second position, each contact member 708 extends outward in theradial direction R4 causing each lower surface 717 to extend at leastpartially in the radial direction R4. Each of the sharp edges 715 ofeach rib 714 apply pressure to the wall or edge of the burr hole H andmay extend outward into the wall or edge of the burr hole H securing theanchor member 700 to the skull S.

The contact members 708 may be actuated between the first and secondpositions by the outer sheath 604. A lower outer sheath portion or joint604 a of the outer sheath 604 is configured to engage with an innercontact surface 710 of the lower anchor portion 706. As the lockingassembly 610 is being secured to the anchor member 700, the threaded top802 and the slotted bottom 804 provide a force to the joint 604 a in theaxial direction A4 that causes each of the contact members 708 to extendoutwards in the radial direction R4.

The burr hole H may have a cylindrical shape that is formed by, forexample, a standard clutch perforator. A diameter of the burr hole H mayhave a substantially similar length as a length of a diameter of thecontact members 708 extending about the axial direction A4 in the firstposition.

The components of the cranial anchoring systems 100, 300, and 600 may bemade of a radiolucent material. In another embodiment the components aremade of a polymer based material which may have radiolucent orradiopaque materials interspersed in the polymer.

One example of a method for using the cranial anchoring system 300commences with taking an MRI of a site of interest within a brain andloading it into a surgical navigation system. Based on the informationfrom the MRI, a surgeon may identify a target point in the brain anddetermine an entry point through the patient's skull S to access thetarget point. Next, a burr hole H is created in the skull S at the entrypoint using, for example, but not limited to, a twist drill having aspecific geometry. In a preferred aspect, the drill is cone shaped toprep the burr hole H for the attachment of the cranial anchoring system300. In a further aspect, the diameter of hole H is the size of astandard drill bit, such as 11 millimeters, 14 millimeters, or 18millimeters. After the hole H is formed, the anchor member 400 isinserted into the hole H, such that the lower anchor portion 406 engagesthe skull S. The ribs 414 and anchor ribs 430 penetrate the skull S atthe edge of the hole H and the tabs 416 contact an inside surface of theskull S, therefore securing the anchor member 400 to the skull S.

After the anchor member 400 has been positioned within the burr hole H,the outer sheath 304 is positioned within the anchor member 400, suchthat the outer sheath 304 is in rotatable contact with the contactmembers 408. The contact between the outer sheath 304 and the contactmembers 408 may further lock the anchor member 400 in place within thehole H by providing a force in the axial direction A3 that is translatedby the contact members 408 to provide a force in the radial directionR3. The radial force further secures the ribs 414 and anchor ribs 430within the edge of the hole H. The locking assembly 310 is positionedwithin the anchor member 400 to secure the outer sheath 304. Prior totightening the locking assembly 310, the outer sheath 304 is rotated toa position that may facilitate access to the target point in the brain.Once the outer sheath 304 is in an appropriate position, the lockingassembly 310 secures the outer sheath from axial, rotational, andcircumferential movement.

The inner sheath 306 is positioned within the outer sheath 304. Theposition of the inner sheath 306 is adjusted by the height adjustmentdevice 308, and is approximated by the navigation system based off ofthe MRI, the reference array(s) 312, the angle of the outer sheath 304,the distance the inner sheath 306 extends through the outer sheath 304,or combinations thereof.

The obturator 313 may be used to facilitate the positioning of the innersheath 306 within the skull S. Once the inner sheath 306 reaches thetarget point, the obturator 313 is removed and an aspirator pump may becoupled to the upper end of the inner sheath 306 via a flexible tube,thereby allowing the removal of the intracranial fluid and tissue.

Although reference was made to the cranial anchoring system 300 in theabove described example for using the cranial anchoring system 300,similar methods may also be employed by the cranial anchoring systems100 and 600.

The cranial anchoring systems 100, 300, and 600 may be used in a varietyof procedures, including, but not limited to, a brain biopsy, anintraventricular surgery, such as a colloid cyst or thirdventriculostomy, intracranial hemorrhage clot removal, and for deepbrain electrode placement.

All references to the disclosure or examples thereof are intended toreference the particular example being discussed at that point and arenot intended to imply any limitation as to the scope of the disclosuremore generally. The scope of the protected innovation is defined by theattached claims.

What is claimed:
 1. A cranial anchor system configured to attach to anopening in a cranium, the system comprising: an anchor member that iselongated along a first axis, the anchor member including: a middleanchor portion defining a middle anchor recess that extends about thefirst axis; and a lower anchor portion extending from the middle anchorportion in a downward direction relative to the middle anchor portionalong the first axis, the lower anchor portion including: a plurality ofcontact members that together define a lower anchor recess, each of theplurality of contact members having: a leg that extends from a bottom ofthe middle anchor portion, each leg having an angular bend defining anupper and a lower section of the leg, a rib mounted to the leg; an outersheath that is elongated along a second axis and defines a firstchannel, the outer sheath including a joint configured to be at leastpartially disposed within the middle anchor recess and the lower anchorrecess such that the joint is rotatable within the middle anchor recessand the lower anchor recess wherein the plurality of contact members areconfigured to be actuated between a first position and a secondposition, wherein in the first position a surface of the lower sectionof the leg extends substantially in the downward direction, and whereinin the second position the surface of the lower section of the legextends at least partially in a radial direction, wherein the radialdirection is substantially perpendicular to the downward direction;wherein the joint is configured to apply a force to the plurality ofcontact members to actuate the plurality of contact members between thefirst position and the second position, and wherein in the secondposition the rib applies pressure to a wall or edge of the opening tothe cranium; a locking assembly configured to provide a force to thejoint in the downward direction; and wherein the lower anchor portionincludes at least one protrusion that extends from an inner surface, andwherein the locking assembly includes a slotted bottom, the slottedbottom having an outer surface that defines at least one slot, whereineach at least one slot is configured to receive each at least oneprotrusion within, and wherein the anchor member further includes anupper anchor portion extending from the middle anchor portion, the upperanchor portion defining a first threaded region, and wherein the lockingassembly further includes a threaded top, the threaded top defines asecond threaded region configured to mate with the first threadedregion.
 2. The cranial anchoring system of claim 1, wherein the slottedbottom extends from the lower anchor portion to the upper anchor portionwhen each of the at least one protrusions of the lower anchor portionare within each of the at least one slots of the slotted bottom.
 3. Thecranial anchoring system of claim 1, wherein the threaded top is coupledto the slotted bottom, and wherein the locking assembly is sized suchthat each of the at least one protrusions of the lower anchor portion isreceived within each of the at least one slots of the slotted bottomprior to the second threaded region of the threaded top being mated withthe first threaded region of the upper anchor portion.
 4. The cranialanchoring system of claim 1, wherein the lower section of the legcomprises a planar surface, and wherein the rib is mounted to the lowersection of the leg.
 5. The cranial anchoring system of claim 4, whereinthe rib includes a sharp edge, wherein the sharp edge extends parallelto the lower section of the leg.
 6. The cranial anchoring system ofclaim 1, wherein the angular bend forms an obtuse angle between theupper section of the leg and the lower section of the leg.
 7. A cranialanchor system configured to attach to an opening in a cranium, thesystem comprising: an anchor member that is elongated along a firstaxis, the anchor member including: a middle anchor portion defining amiddle anchor recess that extends about the first axis; and a loweranchor portion extending from the middle anchor portion in a downwarddirection relative to the middle anchor portion along the first axis,the lower anchor portion including: a plurality of contact members thattogether define a lower anchor recess, each of the plurality of contactmembers having: a leg that extends from a bottom of the middle anchorportion, each leg having an angular bend defining an upper and a lowersection of the leg, a rib mounted to the leg; an outer sheath that iselongated along a second axis and defines a first channel, the outersheath including a Joint configured to be at least partially disposedwithin the middle anchor recess and the lower anchor recess such thatthe joint is rotatable within the middle anchor recess and the loweranchor recess; and wherein each of the plurality of contact members isspaced circumferentially about the lower anchor portion, and whereineach rib is mounted to at least one of the upper section of the leg orthe lower section of the leg, and wherein each consecutive pair of theplurality of contact members includes a rib mounted on the upper sectionof the leg and a rib mounted on the lower section of the leg.
 8. Thecranial anchoring system of claim 7, wherein the lower section of theleg comprises a planar surface, and wherein the rib is mounted to thelower section of the leg.
 9. The cranial anchoring system of claim 8,wherein the rib includes a sharp edge, wherein the sharp edge extendsparallel to the lower section of the leg.
 10. The cranial anchoringsystem of claim 7, wherein the angular bend forms an obtuse anglebetween the upper section of the leg and the lower section of the leg.